Is it possibe to use the --limit query based on the contents of one of the sample tables

[mehulp118]

Say I had tables school, class.

If I dumped 100 classes from the class table and it depends on schools. Can I then put a limit such as school = pg_sample.classes = school_ids (meaning I want to get only the schools that exist in the classes that were pulled by pg_sample already)?

[mla]

I think you should be able to achieve that with --limit='schools=0' which says not to include any rows from the schools table. If the resulting sample data has FKs to school rows though, then those will still be pulled in.

[mehulp118]

Ah, what I mean was what if there is no FK on schools for the classes table? I have a situation like this where the tables don't have that dependency unfortunately but I would still like to pull the data properly as such

[mla]

I see. Hmmm. The problem is going to be the order of the fetching, b/c we don't know when the schools table will be sampled.

So, idk... you could try something like --limit="schools=school_id IN (SELECT school_id FROM _pg_sample.public_classes)" but I doubt that's going to work great.

We have --keep and --data-only options. So theoretically you could run it the first time and --keep the sample tables around. Set --limit="schools=0" on that run. And then on the second run, specify --limit="schools=school_id IN (SELECT DISTINCT school_id FROM _pg_sample.public_classes)" --data-only

But I don't see a way to restrict to a single table for that second run. We allow you to only sample one schema, but not a specific table AFAIK. We could add that.